Abstract:

The microwave extraction technology of brown pigment from Camellia oleifera shells was optimized by L9(34) orthogonal array design and the stability of the pigment was studied. The optimal technological conditions were determined as follows: microwave irradiation time 240 s, microwave power 320 W, extraction solvent 70% ethanol and ratio of material to solution 1:10 (g/ml). A yield of brown pigment of 5.92% was achieved under these conditions. This pigment was found to have a brown-red color and stable to natural light, ultraviolet radiation, temperature, oxidizing agent, reducing agent and some metal ions such as K+, Ca2+, Cu2+, Zn2+, Ba2+ and Mg2+. In pH 2－7, it was also stable. Alkali had hyperchromic effects on the pigment, while Fe3+ had hypochromic effect.

Key words: Camellia oleifera shells, pigment, microwave irradiation, extraction, stability